Many types of disposable absorbent products, such as diapers, are available that have a high capacity for absorbing urine. Disposable products of this type generally comprise some sort of fluid-permeable topsheet material, an absorbent core, and a fluid-impermeable backsheet material.
One substance that has been applied as a lotion to absorbent products to impart a soothing, protective coating is mineral oil. Mineral oil (also known as liquid petrolatum) is a mixture of various liquid hydrocarbons obtained by distilling the high-boiling (i.e., 300°-390° C.) fractions in petroleum. Mineral oil is liquid at ambient temperatures, e.g. 20°-25° C. As a result, mineral oil is relatively fluid and mobile, even when applied to article topsheets.
Because mineral oil is fluid and mobile at ambient temperatures, it tends not to remain localized on the surface of the topsheet, but instead migrates through the topsheet into the interior of the diaper. Accordingly, relatively high levels of mineral oil need to be applied to the topsheet to provide the desired therapeutic or protective coating lotion benefits. This leads not only to increased costs for these lotioned products, but other detrimental effects as well.
One of these detrimental effects is a decrease in the fluid handling properties as high levels of mineral oil tend to block the topsheet openings. Also, as mineral oil migrates to the interior of the article, it tends to act as a hydrophobic additive, thus decreasing the absorbency of the underlying absorbent core, if one is used. This decrease in absorbency becomes more pronounced as the level of mineral oil applied is increased.
Even without increasing its level, the tendency of mineral oil to migrate once applied has other detrimental effects. For example, the applied mineral oil can transfer to, into and through the packaging or wrapper material for the lotioned product. This can create the need for barrier-type packaging or wrapper films to avoid smearing or other leakage of mineral oil from the product.
Accordingly, it would be desirable to provide lotioned absorbent products that: (1) have desirable therapeutic or protective coating lotion benefits (2) do not require relatively high levels of coatings that are liquid at room temperature (e.g., mineral oil) (3) do not adversely affect the absorbency of the absorbent product; and (4) do not require special wrapping or barrier materials for packaging.
U.S. Pat. No. 3,585,998 to Hayford et al. teaches a disposable baby diaper, an interior liner of which carries an array of pressure-rupturable capsules containing baby oil. The patent teaches that it is desirable to break the capsules prior to using the diaper by applying pressure with such household items as a rolling pin, hand iron, etc. The same principle of pressure-rupturable capsules is used in U.S. Pat. No. 3,464,413 to Goldfarb et al. for making bandages capable of delivering a medicinal material to an injury. Articles disclosed by both patents have a serious drawback. Namely, unless the capsules are ruptured by applying pressure prior to using the diaper or the bandage, the skin-care substance contained in the capsules is either not delivered at all or is delivered non-uniformly leaving some areas of skin uncoated.
U.S. Pat. No. 3,896,807 to Buchalter teaches an article impregnated with a solid oil phase of cream formulation which forms a cream upon addition of moisture thereto. A major disadvantage of the article disclosed by the reference is that transfer of a beneficial substance from the absorbent substrate to skin is delayed and is only realized when body fluids are released.
U.S. Pat. No. 3,489,148 to Duncan et al. teaches a baby diaper comprising a hydrophobic and oleophobic topsheet wherein a portion of the topsheet is coated with a discontinuous film of oleaginous material. A major disadvantage of the diapers disclosed in the Duncan et al. reference is that the hydrophobic and oleophobic topsheets are slow in promoting transfer of urine to the underlying absorbent cores.
Therefore, it is an object of the present invention to provide a disposable absorbent article having a hydrophilic topsheet having superior fluid handling properties.
It is a further object of the present invention to provide a hydrophilic absorbent article topsheet having a lotion coating on the outer surface of the topsheet that is transferable to the wearer's skin.
These and other objects are obtained using the present invention, as will become readily apparent from a reading of the following disclosure.